1. Field of the Invention
The present invention relates to a system and method for spatial deinterlace, and more particularly to a system and method for edge direction detection for spatial deinterlace.
2. Description of the Related Art
Deinterlacing is a process of converting interlaced video into a non-interlaced form. However, deinterlacing will produce some image degradation since it ideally requires “temporal interpolation,” which involves guessing the movement of every object in the image and applying motion correction to every object. Interlaced display draws only half of the lines on the screen for each frame, that is, odd lines or even lines alternatively. When video is displayed on a display that can support so high a refresh rate that flickers are not perceivable, interlaced video can be deinterlaced for better viewing. Likewise, when a display must draw the entire screen each time, the video signal must be deinterlaced before it is shown. Right now, all displays except for CRT screens require deinterlace.
One of the popular methods for deinterlace is field combination deinterlacing, which requires interpolation between different fields. In many situations, the interpolation step is done by prediction based on the current field. For example, it is common to determine the direction of edges on the basis of spatial information of the odd field (line 1, line 3, line 5, etc.), and then interpolates data in even lines, such as line 4 according to the edge direction. The display quality of the interpolation partly depends on the search range for the prediction of the edge direction. If the search range is too broad, the determination will be interfered with, and some undesired noises occur. If the search range is too narrow, the determination will probably be wrong.
Because the edge direction detection for spatial deinterlace obviously affects the quality of the display, providing a suitable system and method to process the detection is a very important issue.